problems4 - diFerence in performance to the signal...

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Digital Modulation 1 - Problem Set 4 Problem 1 (4PAM) Consider a 4PAM modulation system. Assume a BSS, an AWGN channel, and an ML receiver. 1. Compute the symbol-error probability of 4-PAM. 2. Compute the approximation for the bit-error probability when Gray-coding is employed. 3. Implement the system in Matlab. Run a a Monte-Carlo simulation and calcu- late the bit-error rate versus the mean SNR for diFerent choices of the encoder mapping enc( · ). Determine the best encoder and the worst encoder. Problem 2 (On-Of Keying) Consider the modulation scheme on-oF keying (cf. previous exercises). Assume a BSS, an AWGN channel and an ML receiver. 1. Determine the decision regions of the optimum vector. 2. Compute the symbol-error probability and bit-error probability. 3. Compare the performance of on-oF keying with that of BPAM. Relate the possible
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Unformatted text preview: diFerence in performance to the signal constellations of the two schemes. Problem 3 (Pulse shaping in MPAM) Assume that the pulse ψ ( t ) of a MPAM communication systems is no longer con±ned to have its support in [0 , T ), where T denotes the signalling interval, i.e., that its time duration is greater than T . 1. Specify the condition that ψ ( t ) has to satisfy such that there is no intersymbol interference (ISI); i.e., such that the output Y n of the demodulator depends (still) only on the transmitted modulation symbol X n , and not on previous or following symbols. (A bit tricky.) 2. Derive the above condition in the frequency domain (Nyquist criterion). (Again a bit tricky.) B²l, TPe. Digital Modulation 1 NavCom...
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This note was uploaded on 12/29/2010 for the course UAE 605 taught by Professor Ttttt during the Spring '10 term at University of Arkansas – Fort Smith.

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